Intuitively, speakers of the same language, depending on their familiarity with other varieties of their language, perceive dialectal, sociolectal, stylistic and idiosyncratic similarities and differences in speed (syllabic duration and tempo), volume (intensity), register (frequency range), melodic patterns (intonation), or rhythm. In the study which originated this article, an attempt is made to identify the acoustic factors that allow this identification, as well as to provide the necessary tools for a systematic analysis like, in this case, a comparative study of the Spanish varieties of Mexico City and Madrid.